The Regional designations of Montana vary widely within the U.S state of Montana. The state is a large geographical area that is split by the Continental Divide, resulting in watersheds draining into the Pacific Ocean, Gulf of Mexico and Hudson's Bay. The state is approximately east to west along the Canada–United States border and north to south. The fourth largest state in land area, it has been divided up in official and unofficial ways into a variety of regions. Additionally, Montana is part of a number of larger federal government administrative regions.
Unofficial designations
Various parts of Montana have been given a number of formal and informal names, including:
Eastern Montana, with varying definitions placing the western boundary anywhere from the Continental Divide to areas east of Billings, Montana.
Western Montana, with varying definitions placing the eastern boundary anywhere from the Continental Divide to the eastern edge of the Absaroka Range.
Central Montana, with varying definitions.
The Hi-Line, a region of northern Montana close to the Canada–United States border along which runs the main line of the Great Northern Railway and U.S. Highway 2.
The "Golden Triangle," an area noted for grain growing, outlined by the cities of Havre, Conrad and Great Falls.
Medicine Line, the name given the 49th parallel border between the U.S. and Canada between Lake of the Woods and the continental divide by Native Americans because of its seemingly magical ability to prevent U.S. soldiers from crossing it.
Yellowstone Country, comprising Carbon, Gallatin, Park, Stillwater and Sweet Grass counties. Includes northern and western gateways to Yellowstone National Park.
Montana east of the continental divide and Wyoming make up the Rocky Mountain Region of the Bureau of Indian Affairs which includes the following Indian agencies in Montana.
The Bureau of Land Management includes Montana with North and South Dakota in its Montana-Dakotas region. The BLM administers Montana through nine regional field offices.
Montana is part of the Western Region of the U.S. Department of Commerce, National Oceanic and Atmospheric Administration's National Weather Service. The NWS maintains four regional offices in Montana.
Billings
Glasgow
Great Falls
Missoula
The NWS designates regional weather reports originating from these offices as Southeastern Montana, Northeastern Montana, Central Montana and Western Montana/Central Idaho.
Montana is included in the Omaha District of the U.S. Army Corps of Engineers Northwestern Division.
Climate regions
In the Köppen climate classification system, Montana is predominantly a BSk climate, with the Mountainous areas, mostly in the western parts of the state, listed as Dfb. Areas near Granite Peak and the highest elevations in Glacier National Park are , and a small area in the northwestern corner of the state near the Idaho border listed as . The United States Department of Agriculture places most of Montana in Plant Hardiness Zones 3 and 4, with limited areas in zone 5 with a small sliver of the state centered in Sanders County in zone 6. These zone boundaries correspond closely to the Köppen classifications. For purposes of the 2009 International Energy Conservation Code, which provides minimum insulation standards for home construction based on climate, the entire state is classified in climate zone 6, requiring higher levels of insulation than are recommended in more temperate climates.
